Variable Meter-Out Restrictor for Hydraulic Actuator Load Control
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Solution Overview
Problem
Construction machines with hydraulic actuators face controllability issues due to changes in the weight and attitude of supported objects, leading to increased meter-out losses and energy losses, as the existing meter-out restrictor designs are optimized for standard attachments and fail to adapt to varying loads and angles.
Innovation Solution
A hydraulic control system with variable restrictors and a load sensor that adjusts the opening area of the meter-out flow passages based on the detected negative load, ensuring optimal control and minimizing energy losses across different load conditions and angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the opening area of the meter-out restrictor is reduced to prevent breathing phenomenon when heavier attachments are used, then controllability is improved, but energy loss increases due to higher pressure loss
Solution Approach 1:
The patent applies dynamics by replacing the fixed opening area meter-out restrictor with a variable opening area meter-out restrictor that dynamically adjusts its opening area based on the actual load conditions. The control device varies the opening area according to the detected load on the hydraulic actuator, allowing the system to adapt to different attachment weights and operating conditions, thus preventing breathing phenomenon only when necessary while minimizing energy loss during normal operation
Solution Approach 2:
The patent implements parameter changes by modifying the opening area parameter of the meter-out restrictor based on load conditions. The control device detects the load on the hydraulic actuator and adjusts the opening area of the meter-out restrictor accordingly, changing this critical parameter to match actual operating conditions rather than maintaining a fixed conservative setting
2Loss of energy
If the opening area of the meter-out restrictor is increased to reduce energy loss, then efficiency is improved, but breathing phenomenon occurs when heavier attachments are used
Solution Approach 1:
The patent implements feedback by using a load detection device to monitor the actual load on the hydraulic actuator and feeding this information back to the control device. The control device then adjusts the opening area of the variable meter-out restrictor based on this feedback, creating a closed-loop control system that responds to actual operating conditions rather than relying on fixed conservative settings
Solution Approach 2:
The system transitions from a static fixed opening area restrictor to a dynamic variable opening area restrictor that continuously adapts its characteristics based on real-time load conditions, allowing optimal performance across varying operating scenarios
3Ease of manufacture
If the meter-out restrictor is designed for standard bucket weight, then manufacturing is simplified, but adaptability to different attachments is reduced
Solution Approach 1:
The patent resolves this contradiction by making the meter-out restrictor dynamic rather than static. Instead of manufacturing different restrictors for different attachments, the system uses a single variable meter-out restrictor that can adapt its opening area electronically based on the attachment being used, maintaining manufacturing simplicity while achieving full adaptability
Solution Approach 2:
The variable meter-out restrictor serves multiple functions and adapts to different attachments, making the hydraulic system universal. A single restrictor design handles various load conditions that would otherwise require multiple specialized restrictors, achieving multi-functionality without increasing manufacturing complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively reduces meter-out losses and energy consumption by dynamically adjusting the meter-out restrictor openings in response to changes in the weight and attitude of supported objects, enhancing the controllability and efficiency of hydraulic actuators in construction machines.
Implementation Method 1
a load sensor for detecting a magnitude of a negative load applied by an external force to the hydraulic actuator in a same direction as an actuation direction of the hydraulic actuator
Implementation Method 2
The meter-out restrictor controls the flow rate of hydraulic fluid discharged from the hydraulic actuator to a tank
Data Source
AI summary
Provided is a hydraulic control system for a construction machine, including: a control valve (31) for controlling supply and discharge of hydraulic fluid to and from an arm cylinder (4); an operation lever (6) for controlling the position of a spool of the control valve (31); a meter-out flow passage (34) for passing therethrough hydraulic fluid discharged from the arm cylinder; a variable restrictor (23a) provided in the meter-out flow passage; pressure sensors (41, 42) for detecting a magnitude of a negative load applied by an external force to the arm cylinder in a same direction as an actuation direction of the arm cylinder; and a controller (45) for reducing an opening area of the variable restrictor (23a) according to an increase in the magnitude of the negative load calculated with a detection value from the pressure sensors (41, 42).